Process for preparing o, o-dihydrocarbon phosphoric acids



United States Patent 3,228,925 PROCESS FOR PREPARING QO-DIHYDRQCUN PHOSPHURIC AQHDS Fred K. Kawahara, Parlr Forest, Iii, assignor to Standard Oil Company, Chicago, Ill., a corporation of Indiana No Drawing. Filed .ln'iy 28, 1961, Ser. No. 127,476 4 Claims. (Cl. 260-971) This invention rel-ates to a process for preparing dihydrocarbon phosphoric acids in high purity.

Dihydrocarbon phosphoric acids, including the dialkyl phosphoric acids, diaryl phosphoric acids, dicycloalkyl phosphoric acids, and the like, are well known in the art. Such compounds are useful as surface-ignition suppressors in motor fuels, such as gasoline, and may be useful in extracting uranium from uranium-bearing ores.

However, it has been difficult, if not often impossible, to prepare the dihydrocarbon phosphoric acids in high purity. Usually, the dihydrocarbon phosphoric acids are prepared -by reacting an alcohol with phosphorus pentoxide but the resulting product contains substantial amounts of monohydrocarbon phosphoric acids. Often it is desirable or necessary to obtain high purity dihydrocarbon phosphoric acids in the substantial absence of the monohydrocarbon phosphoric acids. For example, the dihydrocarbon phosphoric acid is the active species in suppression of surface ignition. Furthermore, the monohydrocarbon phosphoric acid often attacks zinc surfaces in gasoline and supply lines and forms an insoluble zinc salt; the Zinc salt of the dihydrocarbon phosphoric acid is soluble in gasoline. Insoluble zinc monohydrocarbon phosphoric acids precipitate and clog feed lines, valves and the like. Furthermore, in the extraction of uranium from ores, it is necessary to use substantially pure dihydrocarbon phosphoric acid in the absence of monohydrocarbon phosphoric acid for elfective extraction.

The process of the present invention produces 0,0-dihydrocarbon phosphoric acids in high purity. In accordance with the present process, 0,0-dihydrocarbo-n dithiophosphoric acids are converted to the corresponding 0,0- dihydrocarbon phosphoric acids by reaction with 2 mols of water per mol of the dihydrocarbon dithiophosphoric acid at a temperature in the range of from about 100 F. to 400 F. The resulting product is dihydrocarbon phosphoric acid in high purity and in the substantial absence of monohydrocarbon phosphoric acid the reaction may be carried out at higher or lower temperatures but such temperatures are not advantageous. At lower temperatures, e.g. 70 F., the reaction may take weeks or months for completion and such reactions are impractical. At higher than about 400 F., degradation of the product may result.

The above process may be used in combination with the formation of the dihydrocarbon dithiophosphoric acid. Accordingly, phosphorus pentasulfide is reacted with an alcohol to form the dihydrocarbon dithiophosphoric acid which is then converted by the above process step to the dihydrocarbon phosphoric acid.

Although the nature and size of the hydrocarbon groups are not critical with respect to this invention and although the process is applicable to the formation of any dihydrocarbon phosphoric acid, where the hydrocarbon (i.e. at least one of the hydrocarbon groups) has less than 8 carbon atoms, e.g. 1-5 carbon atoms, it has been found advantageous to carry the reaction out at a temperature in the range of 150 to 250 F. and preferably about 200 F. Similarly, where the hydrocarbon contains about 8 carbon atoms, it has been found advantageous to conduct the reaction at a temperature in the range of 200 to 300 F. and preferably about 220 to 240 F. Additionally, where the hydrocarbon groups contain more than 8 carhon atoms, it is advantageous to conduct the reaction at a temperature in the range of 200 to 350 F. and preferably 220 to 300 F.

In addition to the above variances in advantageous temperature ranges for reactions to form dihydrocarbon phosphoric acids wherein the size of the hydrocarbon group varies, it has been found advantageous to employ a solvent in the case Where the hydrocarbon group is less than C Such solvent may be diluent capable of thinning the reaction mixture, e.g. ketone (acetone), ether, dioxane, isooctyl, hexyl, etc.; the solvent may be an excess of the alcohol used in the formation of the dihydrocarbon dithiophosphoric acid. Where the hydrocarbon group is about a C it is advantageous to use in addition to a solvent, an emulsification agent to mix the water and dithiophosphoric acid phase. Such emulsification composition may be non-ionic, e.g. an ester, amid-e or polyether ethanol detergent, or may be cationic, e.-g. quaternary ammonium chlorides or nitrites, or may be anionic, e.g. sodium dodecyl phenyl sulfonate. Where the hydrocarbon group is higher than C the alcohol solvent and detergent or emulsification agent are also employed.

In the reaction of this invention, 2 mols of water are reacted with the dihydrocarbon dithiophosphoric acid to produce the corresponding dihydrocarbon phosphoric acid. It is preferred that an excess of the water he used, e.g. 2 to 3 mols of Water per mol of dithiophosphoric acid during the reaction. The dihydrocarbon phosphoric acid product is recovered as the non-aqueous phase where it is water-insoluble or may be recovered by evaporation of excess Water where it is water-soluble.

Examples of dihydrocarbon dithiophosphoric acids which may be used in the present process include the di(C to C hydrocarbon dithiophosphoric acids, e.g. the dialkyl, diaryl, diaralkyl, dicycloalkyl, etc., dithiophosphoric acids, such as 0,0-dimethyl dithiophosphoric acid, O-butyl, O-octadecyl dithiophosphoric acid, 0,0-dibutyl dithiophosphoric acid, 0,0-diisooctyl dithiophosphoric acid, 0,0-didodecyl, 0,0-diisopropyl dithiophosphoric acid, 0,0-dihexyldecyl dithiophosphoric acid, 0,0- dioctadecyl dithiophosphoric acid, 0,0didocosyl, 0,0-diphenyl dithiophosphoric acid, 0,0-ditoluyl dithiophosphoric acid, 0,0-dinaphthyl dithiophosphoric acid, 0,0- dianthryl dithiophosphoric acid, 0,0-dixylyl dithiophosphoric acid, 0,0-dicyclohexyl dithiophosphoric acid, 0,0- dicyclopropyl dithiophosphoric acid, 0,0-dicyclooctyl dithiophosphoric acid, 0,0-isopropyl, 0,0-decyl dithiophosphoric acid, 0,0-isopropyl, 0,0-isooctyl, 0,0-octadecyl, 0,0-tolyl dithiophosphoric acid, 0,0-cyclohexyl O-hexyl, O-Z-naphthylethyl, O-methyl dithiophosphoric acid, 0- methyl O-amyl dithiophosphoric acid, 0,0-diamyl dithiophosphoric acid, and the like.

As disclosed hereinabove, the dihydrocarbon dithiophosphoric acid may be produced as a first step in an em bodiment of this invention. Accordingly, the corresponding alcohol is reacted with the phosphorus pentasulfide. Four mols of the alcohol are included in the reaction mixture per mol of phosphorus pentasulfide (P 8 and the reaction may be carried out at a temperature in the range of from about to 400 F. Useable alcohols are evident from the above examples of dihyd-rocarbon dithiophosphoric acids, such useable alcohols including, for example, the corresponding hydroxy substituted hydrocarbons of the hydrocarbon radicals disclosed as O- substituted in the dithiophosphoric acids, e.g. methyl alcohol, isopropanol, phenol and the like.

In order to illustrate the process of the present invention, 144 g. of isopropyl alcohol are added gradually to 111 g. of phosphorus pentasulfide at a temperature in the range of F. to F. and reacted at that temperature for 1 hour. Thereafter, 36 g. of Water are added and the reaction mixture is maintained at a temperature of 170 F. for 16 hours. The resulting product is d-iisopropyl phosphoric acid containing no more than trace amounts of monoisopropyl phosphoric acid.

As another example of a preparation in accordance with the process of this invention, 144 g. of isooctyl alco- 1101 are reacted with 56 g. of P 3 in 44 g. SAE 5 oil as a diluent. The reaction mixture is maintained at a temperature of 240 to 260 F. for 2 hours. 18 g. of water are then added and the mixture is maintained in the 220 to 240 F. range for about 24 hours. The product is diisooctyl phosphoric acid.

The dihydrocarbon phosphoric acids in substantially pure form as produced by the present process may be 1 used, in addition to use assurface ignition suppressors and uranium extraction agents, as'intermediate in the produc tion of addition agents and especially addition agents for use in gasoline. As an intermediate, the product may be used to form the amine salt which may be used as a de-icing agent in gasoline. In the form of the amine salt, the acid is completely tied up and'the resulting composition would be substantially non-corrosive to Zinc parts.

It is evident from the foregoing that I have provided a process for making dihydrocarbon phosphoric acids in the substantial absence of the monohydrocarbon phosphoric acid.

I claim:

1. A process for making 0,0-dihydrocarbon phosphoric acids which process comprises reacting 0,0-dihydrocarbon dithiophosphoric acid wherein the dihydrocarbon group is selected from the class consisting of alkyl, phenyl, alkylphenyl, dialkylphenyl, naphthyl, anthracyl and naphthylalkyl radicals with two mols of water per mol of said acid at a temperature in the range of from about F. to about 400 F. and recovering the resulting corresponding dihydrocarbon phosphoric acid in the substantial absence of corresponding monohydrocarbon phosphoric acid.

2. The process of claim 1 wherein said reacting is carried out in the presence of a solvent for said 0,0-dihydrocarbon dithiophosphoric acid, and said Water and 0,0- dihydrocarbon dithiophosphoric acid are present in the reaction mixture in the form of an emulsion.

3. The process of claim 1 wherein the 0,0-dihydrocarbon groups of the 0,0-dihydrocarbon dithiophosphoric acid and the resulting phosphoric acid are diisopropyl groups and acid reaction temperature is in the range of t0 250 F,

References Cited by the Examiner UNITED STATES PATENTS 2,7 15, 136 8/1955 Toy et al. =260-461 2,863,902 12/ 1958 Santay 260-'46-1 2,996,533 8/1961 Millikan et al. 260-461 3,073,857 1/'1963 Millikan et al. 260-461 OTHER REFERENCES Pishchimuka: Chem. Abst., vol. 20, p. 2816 (1926).

CHARLES B. PARKER, Primary Examiner.

NORRIS LIEBMAN, IRVING MARCUS, Examiners. 

1. A PROCESS FOR MAKING O,O-DIHYDROCARBON PHOSPHORIC ACIDS WHICH PROCESS COMPRISES REACTING O,O-DIHYDROCARBON DITHIOPHOSPHORIC ACID WHEREIN THE DIHYDROCARBON GROUP IS SELECTED FROM THE CLASS CONSISTING OF ALKYL, PHENYL, ALKYLPHENYL, DIALKYLPHENYL, NAPHTHYL, ANTHRACYL AND NAPHTHYLALKYL RADICALS WITH TWO MOLS OF WATER PER MOL OF SAID ACID AT A TEMPERATURE IN THE RANGE OF FROM ABOUT 100*F. TO ABOUT 400*F. AND RECOVERING THE RESULTING CORRESPONDING DIHYDROCARBON PHOSPHORIC ACID IN THE SUBSTANTIAL ABSENCE OF CORRESPONDING MONOHYDROCARBON PHOSPHORIC ACID. 